Etckeeper

Etckeeper is now installed on Charity, which means the correct procedure after making edits to files in /etc is to issue:

$ sudo etckeeper commit "my reasoning here"

after you're done with your changes. There's an auto commit every day, and an autocommit whenever you apt-get install something. You can manually commit your changes as above. To see the commit log for a particular file:

$ sudo bzr log /etc/passwd

To revert an unwanted or bad change, work out which revision you want to revert to (see log above) and run:

$ sudo bzr revert --revision <commit number> <file>

For example, to restore the /etc/passwd file to the state it was in in revision 3,